Pitch composition and method of making same



Sept. 5, 1933.

S. P. MILLER- 1,925,150

PITCH COMPOSITION AND METHOD OF MAKING SAME Filed Aug. 17, 1927 2Sheets-Sheet 1 INVENTOR WWW ATTORNEYS Sept. 5, 1933. v s MlLLER v1,925,150

PITCH COMPOSITION AND METHOD OF MAKING SAME Filed Aug. 1'7, 192'? 2Sheets-Sheet 2 INVENTOR ATTORNEYS Patented Sept. 5, 1933 rrrcnCOMPOSITION AND METHOD or MAKING SAME Stuart Parmelee Miller, GlenRidge, N.J., assignor to The Barrett Company, New York,

N. Y., a corporation of New Jersey Application August 17, 1927. SerialNo. 213,497

2 Claims. (Cl. 202-30) This invention relates to a new pitch compositionand to an improved method for producing the same. The invention alsoincludes improvements in distillation of tar, and in the recovery 5 andproduction of valuable products therefrom.

In order to produce heavy or high boiling pOint oils from tar byordinary distillation methods, it is necessary to carry the distillationto a high temperature. Such distillation is accompanied with a veryconsiderable decomposition of oil constituents of the tar, so that theyield of oils recovered by distillation is considerably less than thatcontained inthe tar distilled, while an increased amount of pitch isproduced, partly by,

decomposition during the distillation, and the pitch has a high carboncontent.

Such distillation of tar is commonly carried outat tar distillationplants located at a greater or less distance away from the coke ovenplant at 29 which the tar is produced. The tar separated from the cokeoven gases by cooling and condensation is collected and transported tothe tar distillation plant and there subjected to distillation. Suchprocedure is accompanied by cost of transportation and losses oftarincidental to its handling and shipment, while the distillation ofthe tar,is accompanied with further loss of oil by decomposition andincrease in the amount of pitch and carbon content of the pitchproduced.

Y 30 as a residue of the distillation. When such high carbon pitch isblended with ordinary tar, the high carbon content of the pitch mayinterfere materially with the blending operation and may result insettling out of some of the carbon with 85 resulting lack of homogeneityof the blended product and with liability pf clogging of pipe lines,etc., where the resulting blended product is used for fuel or otherpurposes.

The present invention eliminates the necessity 4| of the transportationof tar from a coke oven oven plant, and distillation is so carried outas to produce a hard or high melting point pitch, which will,nevertheless, have a much lower carbon conby the hot coal distillationgases.

tent than the pitch produced by ordinary tar distillation methods inexternally heated tar stills; and this pitch directly produced by suchdistillation is then blended with tar to form a composite productvaluable, for example, for use 80 as a fuel composition in open hearthfurnaces, etc. The production of the pitch in this way,

is accompanied by the production of a high yield of oils, includingheavy or high boiling point oils, and including oils which, in ordinarytar distillation methods, are decomposed and converted into a pitchresidue or into carbon or other decomposition products.

The gases from coke ovens or retorts leave the ovens at a hightemperature, around 600 to 700 C. or higher, and are commonly cooled inthe collector main of the battery by the introduction I of ammonialiquor or ammonia liquor and tar, directly into the collector main tothrow down a heavy tar from the gases, and by further cooling of thegases in the coolers or condensers to throw 'down a light tar or tarryoil therefrom. The heavy tar and light tar are commonly mixed andsubjected to distillation. The tar so produced may be employed in theprocess of the present invention, and may be tar produced at the samecoke oven-plant at which the distillation is carried out or it may becoke oven tar produced at another coke oven plant, or may be in part gashouse tar or water gas tar, etc.

According to the present invention, the tar is subjected to distillationby bringing it into direct contact with the hot coke oven gases at asulficiently high temperature to distill the tar to remove a large partof the oil components thereof, and to leave a pitch residue of highmelting point but of relatively low carbon content; and the resultingpitch is then blended with raw tar or with heavy tar, etc., to form thenew pitch composition. The distillation of the tar in direct contactwith the hot coke oven gases can be carried out, for example, inaccordance withathe processes described in my prior applications, SerialNos. 166,081, 171,955, 172,962, and 181,366, by spraying the tar intothe hot coke oven gases at a temperature not greatly below that at whichthe gases leave the ovens, so as to use the high temperature of thegases for the distillation. Such distillation will take place withoutexternal heating of the apparatus in which the distillation takes place,and with heating of the tar only This distillation will remove from theindividual particles of tar sprayed into-the gases a large part of thevaporizable components, leaving a pitch residue v which will vary in itsmelting point with the exthe tar. is not kept in contact with the hotgases for a prolonged period, can be carried out without anyconsiderable increase in carbon content due to decomposition during thedistillation, although some such decomposition may take place,particularly where the time of contact of the tar and resulting pitchresidue with the hot gases is prolonged. In any event, the pitch residueproduced will be of relatively much lower carbon content than pitchresidues produced by distillation in ordinary externally heated tarstills, while a considerably increased oil yield can be obtained bydistillation from the same amount of tar, as compared with the oil yieldproduced by distillationin ordinary tar stills. The present invention,accordingly, forms valuable process for the distillation of tar where apart only of the tar is to be distilled, and where the maximum oil yieldis desired from the tar and where the pitch residue is to be employedfor blending with the remainder of the tar for fuel or other purposes.

The distillation of the tar and the production of the pitch, accordingto the present invention, are advantageously carried out as a continuousoperation, with the continuous production of a hard, high melting pointpitch, and with the continuous blending of such pitch with raw tar toproduce the new composite pitch composition. The tar can be introduced,for example, directly into a still through which the hot coke oven gasesare passing and the rate of distillation regulated or the tarrecirculated and further distilled, to givecontinuously a high meltingpoint pitch; and this pitch as produced can then be advantageouslyblended continuously'with a stream of raw tar to form continuously theblended composite pitch products.

The hot coke oven gases coming from the individual coke ovens at a hightemperature are capable of distilling an amount of tar many times thatwhich is produced from the gases from a single oven. Accordingly, in acoke oven plant where the tar to be distilled is that produced at thesame plant, the gases from a few only of the ovens will suifice for thedistillation of the tar produced from the remainder of the battery.Where, however, the tar from several batteries is to be distilled, thegases from an increased number of ovens, or from an entire battery, orfrom so much of a battery as is connected to a single collector main,may be employed for the distillation. By bringing the tar intimatelyinto contact with the hot gases at substantially their maximumtemperature as they leave the coke oven, the tar can be continuouslydistilled in a single operation to produce substantially the maximumyield of distillate and a hard high melting point pitch residue, whichcan be drawn off continuously and blended continuously with raw tar,etc., to form the new pitch composition. In order to obtainsubstantially the maximum yield of distillate, the distillation can becarried to such an extent that pitch of high melting point, for example,pitch of 300 F. melting point, can be produced; but the furtherdistillation can advantageously be carried to such an extent that a muchhigher melting point pitch is produced, such as a pitch of melting pointaround 400 F., or in some cases as high as 500 F. The di illighter oils,blend therewith to form a homogeneous product. r

The blending or mixing of the pitch with the tar can be carried out assuccessive batches by adding the hot pitch gradually to a tank ,of hottar, or vice versa. It can also advantageously be carried out in acontinuous manner by running streams of pitch and tar continuously intoa" mixing box or receptacle in which the streams blend and mix with eachother to form a homo-' geneous product, with further agitation, ifnecessary, and by continuously discharging the resulting homogeneousmixture from the mixing chamber. When tar is distilled'to produce pitchof highmelting point, and where the pitch is directly blended with rawtar, the hot pitch will heat the tar and result in a heated mixture fromwhich moreor less distillation may take place, due to the heating of thetar to a temperature above the distillation temperature of some of itsconstituents. tar may be removed and recovered as a distillate oil, ormay be refluxed back and blended with the pitch composition. Raw tarwhich contains water will be dehydrated by the mixing operation, but byrunning streams of the raw tar and hot pitch into a mixing box, anyfoaming due to the removal of water will be taken care of withoutinterfering with the mixing operation.

The resulting blended product made by blending the hot pitch and tar canbe employed for various purposes, such as for fuel purposes, as fuel inopen hearth furnaces, etc.; or it can be employed for other purposeswhere a blended pitch and tar product is desired, for example, forroad-making purposes, or for roofing, etc.

The tar which is blended with the hot pitch may be part of the tarproduced at the same coke oven plant, or it may be tar from anotherplant, or gashouse tar, etc. tar, including both the heavy tar from thecollector main and the light tar or tarry oil from the condenser, onlythe heavy tar from the collector main may be blended with the hot pitch,

leaving the tarry oil from the condensers to be employed for otherpurposes. Such tarry oil can advantageously be blended with thedistillate condensed from the enriched gases resulting from thedistillation of the tar and production of the pitch, and a blendedproduct may thus be obtained which can be employed directly forcreosoting or other purposes. The present invention includes theproduction of such a blended productfrom the distillate and from lighttarry oils as Well as the production of a composite pitch product fromthe pitch residue of the distillation and the heavy tar from thecollector main.

The distillation of the tar by the hot coke oven gases will result in avery material enrichment of the gases in oil vapors, and the oilcondensed from the resulting enriched gases will contain a relativelylow content of heavy tarry matter, since they will be made up largely ofthe distillate oils and will contain a relatively small amount of oilsand heavy tar directly condensed from the gases employed for thedistillation and originally carried thereby before the enrichment by thedistillation. The enriched gases can be employed with whatever heavy taror pitch constitutents they contain and blended,

Instead of using the total The oils so distilled from the ,for example,with the light tar or tarry oilsdirectly produced from coke oven gasesin the ordinary condensers or coolers of the by-productrecovery system.In such case, only the heavy tar from the collector mains may besubjected to distillation for the production of the pitch residue, andthe light tar or tarry oils from the condensers may be kept separate andblended with the distillate from the distillation of the heavy tar insuch proportions as will give, for example, a creosote compositionsuitable for use as asubstitute for ordinary coal tar solution. -Such acreosote composition is describedin my prior application, Serial No.199,629.

The gases produced by the distillation can be subjected to a cleaningtreatment at a high temperature with an electrical precipitator toremove suspended pitch particles therefrom, and to leave only gasescarrying only clean oil vapors, from which clean oils free from tar canthen be directly condensed. In this case an added amount of pitch willbe recovered from the electrical precipitator, which may be blendedwiththe pitch resulting from the distillation. In this case; only pitchand clean oils will resultfrom the distillation, and the clean oils maybe recovered as merchantable oils, for example, clean creosote oils, oras a creosote oil fraction and a tar acid oil fraction, as described,for example, in my companion applications Serial Nos. 206,366 and206,367.

The new pitch composition of the present invention differs greatly fromcompositions made by mixing tar with pitch produced by distilling tar insimple, externally heated tar stills. In

such stills of, for example, 10,000 gallons capacity,

where successive charges of tar are heated and distilled by theapplication of external heat to the still, the yield of distillateoil isrelatively. small, and the amount of pitch produced is large and thepitch is high in free carbon, and particularly in carbon produced bydecomposition during the distillation. Tar distilled in such stills toproduce a pitch of melting point around 170 F. gives an oil yield ofonly about 33 per cent of the tar distilled; if the distillation iscarried further to produce a pitch of around 200 F. melting point, theoil yield is only about 38 per cent,

while if the distillation is carried still further to produce a pitch ofaround 300 F. melting point, the oil yield is increased only to about 44per cent, and coking of the tar may begin before pitch of a meltingpoint of around 400 F. is

reached. The distillation of tar with hot coke oven gases, as carriedout in producing the new pitch composition, gives a radically increasedyield of oils and a corresponding reduction in the amount of pitch andan entirely different character of pitch. For example, 'in distillingcertain coke oven tars by direct contact with hot coke oven gases wherethe time of contact is short, the distillation of the tar to produce apitch of a melting point around 170 F. gives an oil yield around 48 percent; while with distillation to produce a pitch residue of meltingpoint around 200 R, an oil yield around 55 per cent or higher can beobtained; and if the distillation is carried so far as to produce pitchof a melting point around 300 R, an oil yield around '70v per cent canbe obtained; and it is possible to carry the distillation to producepitch of 400 F. melting point and higher, with a yield, for example,around percent of oil when 400 F. melting point pitch is produced.Comparing, ior example, the pitches of melting point around 300 F.produced respectively in ordinary externally heated tar stills of thetype above mentioned, and pitch of similar melting point produced bydirect distillation with hot coke oven gases, it will be seen that theyield of oils is only about 44 per cent in\one case and around 70 percent in the other. The remaining 26 per cent of oil is largelydecomposed by the distillation in the ordinary tar stills, with increasein pitch residue. Moreover, this decomposition, due'to localoverheating, etc., results in production of l a large amount of carbon,and of carbon of a diiferent character. It includes not only substancescommonly called carbon because insoluble in benzol, but it containsconsiderable elemental carbon or decomposition products insoluble, forexample, in anilin, while the so-called carbon contained in the pitchemployed in the new composition is readily soluble in anilin and iscomposed of heavy hydro-carbons, which are readily soluble in, or form ahomogeneous composition with, the tar with which the pitch is blended.The ayoidance of the large; increase in carbon of a difierent characterin the pitch products employed in the new composition gives an improvedcomposition from which there is little, if any, liability of carbonsettling out, for example, in pipe lines by 'whichthe composition issupplied to fuel burners. v

The invention will be further described in connection with theaccompanying drawings, which illustratein a somewhat conventional anddiagrammatic manner an arrangement of apparatus suitable for thepractice of the invention.

In the accompanying drawings,

Fig. 1 shows an arrangement of part of a coke oven plant with part ofthe by-product recovery system, including an arrangement for distillingtar by direct contact with hot coke oven gases; and

Fig. 2 is an elevation with parts in section of the short collectorinain and electrical precipitator of Fig. 1..

In the accompanying drawings, the coke oven 1 has the usual uptake pipes2 leading to the ordinary collector main 3, having center box 4 andcross-over main 5 for leading the gases to the condensers shown as 6 and7, which are of the direct type cooled by introduction of coolingliquid, such as water or ammonia liquor, through. the pipes 8, Fromcondensers the gases pass to the exhauster 9, and then to the ammoniaabsorber and light oil scrubber (not shown).

Ammonia liquor, or'zammonia liquor and tar, is

and to flush the tax; from the collector main 4 through the center box.The outlet for tar and. liquor is indicated at 10 and leads totheseparator or decanter 11, from which the tar flows to the tar storage orreceiving tank 12, and the ammonia liquor to the tank 13. The line 15,with pump 14 in it, conveys tar toa short collector main 21 fordistillation.

The tarry oils condensed in the condensers 6 and 'I are run ofi throughlines 16 and 17 and may be collected together in the receiver ordecanter 18, from which the ammonia liquor is collected in the receiver20,'and the tarry oils in the short collector main for suchdistillation. The

tar is introduced into the short collector main through spray nozzles23, and is brought into intimate contact with the hot gases passingthrough I the short collector main, and is thereby distilled and a pitchresidue produced. A pump 14' is provided through which the pitch residuemay be recirculated. The hot gases coming from the individual ovens areat a high temperature, around 600 to 700 C. or higher, and withinsulation of theindividual uptake pipes and of the shortcollector main,these gases enter the short collector main without any considerablereduction in temperature, so that they are available at a hightemperature for distillation of the tar. By regulating the tar supply,and by recirculating the resulting pitch if necessary, the tar can bedistilled to produce a pitch of high melting point, from which a highyield of oils is driven off.

The pitch residue from the distillation goes through the line 24 to amixing tank or chamber 25, to which tar' is also supplied in regulatedamounts through the line 26. With continuous distillation of tar andcontinuous production of pitch, the pitch can be supplied continuouslyto the mixing chamber, together with continuous supply of tar inregulated amount so that the pitch and tar will continually mix in themixing chamber and the mixture will flow out through the outlet 30 tothe receptacle 31 for the mixed product.

The hot pitch will enter the mixing chamber 25 at a high temperature,while crude tar, or even wet tar, may enter through the line 26 at ordinary temperature. The heat of the hot pitch will serve to heat the tarwith which the pitch admixes, and this in turn willserve to dehydratethe tar and removetherefrom more or less of the oils volatile at thetemperature of the resulting mixture. Some foaming may take place wherethe hot pitch and the wet tar come into contact with each other, butthis will be unobjection'able, because the mixing chamber 25 can be keptnearly empty, that is, with only a layer of thefiowing mixture in thebottom, so that any foam formed will be taken care of. The-mixingchamber 25 may be supplied with an agitator to promote the intermixtureof the tar and pitch, but, ordinarily this will not be necessary whereregulated streams of the two materials are suitably brought together inthe mixing chamber. The hot pitch, because of its low carbon content,and because the carbon content which it contains is largely made up ofheavy hydrocarbons, readily blends with the tar to form a substantiallyhomogeneous mixture with little, if any, tendency for the separation ofcarbon therefrom during storage and circulation to burners, etc. A

Oils vaporized in the mixing chamber can be condensed by the condenser27 and either re turned to the mixture of tar and pitch through the line28, or drawn off as condensate through.

the line 29 and employed as an oil for other purposes.

be materially enriched in vapors due to the distillation. These gasespass through the line 32 to the condensing-system shown in twocondensers 34 and 35. The gases may be passed to this condenser withoutfurther treatment by cleaning, but are advantageously subjected tocleaning with an electrical precipitator at a high temperature torecover suspended pitch particles therefrom rating the suspended pitchparticles therefrom,

' covered in the main condensing system in proper a pitch in the form ofa pitch product which can advantageously be added as part of the newfuel composition. The gases from the short collector main will leave itwhile still at a high temperature, and if passed through the electricalprecipitator without material cooling, will carry pitch particles ofrelatively a high melting point pitch and will carry a large amount ofoils in the form of vapors. By treating the gases and sepathe pitch canbe employed in making the new pitch composition while the gases can besubjected to cooling and condensation to recover directly therefromclean oils, free or substantially free from heavy tar and pitchimpurities. These clean oils will be condensed in the condensers 34 and35 which may be of the indirect type, i. e., cooled by indirect contactwith water, so that a heavy creosote'oil and a lighter tar acid oil canbe directly recovered therefrom. The gases then pass to the exhauster 36and to an ammonia absorber, etc., (not shown).

The clean oils recovered in the condensers 34 and 35 may be blended withthe tarry oils reproportions to give a creosoting composition; or onlythe heavy condensate from the condenser 34 may be so employed. If thegases are not cleaned with an electrical precipitator, they will carrymore or less heavy tar and pitch constituents with them, and the oilscondensed in the condensers 34 and 35 .will be tarry oils. They willdiffer materially, however, from the tarry oils collected in thereceiver 19, because they will be recovered or condensed from enrichedgases, and willcontain relatively little pitch and heavy t'arconstituents. The tarry oils from the respec- 'tive systems canadvantageously be blended in proper proportions to give directly acreosoting composition suitable for use as an improved sub- 5 stitutefor coal tar solution.

The apparatus illustrated includes the byproduct recovery system of anordinary coke oven plant in which ammonia liquor is employed for coolingthe gases in the collector main, and in 2 which a heavy tar is separatedfrom the collector main and tarry oils from the condensers. In

addition, the apparatus illustrated includes a tar still for distillingthe tar by direct contact with hot coke oven gases from part of thebattery so.

as to produce from this tar a pitch residue and distillate. oils whichmay be clean distillate oils,

or which may be tarry oils. The pitch residue is then blended with tarto'form the new fuel composition. The oils resulting from thedistillation may likewise be blended with the tarry oils from theordinary recovery sytem to make a creosoting composition, while 0 y theheavier tar from the collectormain of the ordinary system may besubjected to distillation to produce 5 I residue and distillatebilsthereform.

The present invention involves the production of a new fuel composition,in which the pitch directly produced by distillation of tar with hotcoal distillation gases and of the distinctive comi position resultingfrom such distillation is blended The gases leaving the short collectormain will with tar or heavy tar or tar from another source such asgashouse tar, or water gas tar, to make a new composite product suitablefor use, for

in a manner which makes the pitch available to advantage for fuel andother purposes. The composite pitch product can be employed, for example, for roofing purposes, or for road treating purposes, etc.Simultaneously with the production of the new pitch composition, theremay advantageously be also produced a creosoting composition by blendingthe distillate oils resulting from the distillation with directlyrecovered tarry oils in suitable proportion.

In this way the total tar produced by the coke oven plant may be used upand converted into the new fuel composition andfmto compositionssuitable for use directly for creosoting purposes. When the tarry oils,as well as the heavy tar from the ordinary by-product system, aresubjected to distillation to produce the pitch for blending to make thenew product and to produce distillate oils, the distillate oils can beemployed as such or blended with other products. Instead of working upall of the tar from the coke oven battery by distillation, part of itmay be employed for blending with the pitch produced by thedistillation, or the pitch so blended may be tar from another source,and even tar of different properties, such as, for example, water gastar. Fuel compositions made from the high melting point low carbon pitchand water gas tar are advantageous, inasmuch as water gas tar itself isnot suitable for distillation to give distillate oils suitable forcertain purposes, such as creosoting purposes, or it gives distillateinferior for that purpose. By subjecting coal tar to distillation torecover creosote oils, and then blending the pitch residue with watergas tar, a valuable fuel composition is obtained.

cooling hot untreated coke oven-gases to sepa-' rate therefrom first aheavy tar and thereafter a light tar, subjecting the heavy tar todistillation by bringing it into direct contact with hot coke ovengases, at substantially the temperature at which they leave the ovens toproduce a pitch residue of high melting point and gases enriched in oilvapors, mixing the resulting hot pitch residue with tar to form ahomogeneous pitch composition, cooling the enriched gases to condenseoil vapors therefrom and mixing the oil condensed from the gases withthe light tar to form a composition suitable for use for creosotingpurposes.

2. The method of producing composite pitch compositions and clean oils,which comprises subjecting tar from gasification or coal carbonizationprocesses to distillation by bringing it into direct contact with hotcoke oven gases to produce a pitch residue of at least 300 F. meltingpoint and gases enriched in oils, subjecting the resulting gases tocleaning with an electrical precipitator to separate suspended pitchparticles therefrom, combining the pitch from the precipitator and thepitch residue from the distillation while still hot and withoutsubstantially increasing the free carbon content of either with tar toform a composite pitch composition, and recovering clean oils from thegases resulting from the distillation.

STUART PARMELEE MILLER.

